The object of this proposal is to describe in detail the characteristics of short and long term retention in senescent C57BL/6 male mice. Animals from age groups 3,6 and 30 months will be trained in both simple and complex avoidance and appetitive instrumental learning tasks. Preliminary experiments will be carried out to determine the specific values of motivational and training variables for each age group which will result in comparable rates of learning. Rate of forgetting will be measured 1, 7, 14 and 28 days following learning. Attempts will be made to alleviate retention deficits in senescent mice by administration of nonadrenergic and dopaminergic receptor agonists. Additional experiments will assess the effect of aging on short term memory measured over retention intervals ranging from 5 to 120 seconds.